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CT60 and related things BBS
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Posted by: evil
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Aug,15.2003-21:33
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Reply to Peters message way below.
Why use c2p and not hicol?
Simple: Hicol will be slower.
The game is 256 colours, and using hicol means twice the amount of data to move into chipram.
As the c2p is "copyspeed" the hicolour solution is at least twice as slow (hicolour needs twice the data plus a coloutable lookup).
8bpl 1x1 c2p manages about 450 lines in 1 vbl on CT60/66-16 RGB/50Hz. To do that in hicolour would need 320*450*2 == 288000 bytes, which is impossible to move even with CT60 72/25 and without the extra colour lookup.
Ok, next obvious idea; why not map right into chipram and do the hicol lookup directly? Well some disadvantages:
- Still twice the data to transfer to chip compared to an 8bit c2p
- If you need to clearscreen doing that in chipram is terrible
- Overlays, texts, anything that does overdraw suffers badly
- Chipram stalls; the c2p is phenomenal and nearly kills off all chipram stalls, I don't think you can have a chance to get the texturemapper into "copyspeed" optimiziation like with a c2p.
And for the sake with just quake is of course that the routines work right off with an 8bit buffer.
I've done some tests with a 6pl c2p (should be enough for nice envmappings etc) and it freaking fast. 625 lines in a vbl or so! Meaning 1/3 vbl for c2p and 2/3 vbl to do the efx.. Can be some nice smooth stuff not possible without CT60 :)
--
Anders Eriksson
ae@dhs.nu
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Posted by
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Date
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moved: why c2p ?
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evil
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Aug,15.2003-21:33
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Re: moved: why c2p ?
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MiKRO
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Aug,15.2003-22:13
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Re: moved: why c2p ?
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evil
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Aug,15.2003-23:16
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Re: moved: why c2p ?
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Anonymous
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Aug,15.2003-23:16
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Re: moved: why c2p ?
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Peter
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Aug,15.2003-23:21
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Re: moved: why c2p ?
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evil
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Aug,16.2003-01:15
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Re: moved: why c2p ?
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earx
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Aug,19.2003-09:03
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Re: moved: why c2p ?
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creature
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Aug,18.2003-21:08
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Re: moved: why c2p ?
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deez
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Aug,19.2003-10:20
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Re: moved: why c2p ?
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creature
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Aug,19.2003-15:19
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Re: moved: why c2p ?
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earx
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Aug,19.2003-11:55
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